A grid reference tells a reader exactly where something is on a map using two numbers: the easting first, then the northing. A four-figure reference names a whole square, and a six-figure reference points to a spot within it. Both appear in map-skills questions across the paper.
This skill opens map reference and direction, and the later lessons use it to describe routes and boundaries.
How does a grid reference work?
The grid is a set of numbered lines. The vertical lines are eastings and their numbers increase as you move east, to the right. The horizontal lines are northings and their numbers increase as you move north, up the page.
For a four-figure reference, find the easting line on the left edge of the square, then the northing line on the bottom edge. Write the easting first. The square whose bottom-left corner is at easting 41 and northing 62 is 4162.
For a six-figure reference, imagine ten equal strips across the square. Count how many tenths the feature is to the right of the easting line, and how many tenths it is above the northing line. Put the tenth digit after each line number.
Worked example
All map details here are invented. A bridge sits 3 tenths of the way across the square, measured from easting line 41, and 7 tenths of the way up from northing line 62.
Step 1, easting: line 41, plus 3 tenths, gives 413.
Step 2, northing: line 62, plus 7 tenths, gives 627.
Step 3, join them, easting first: 413627.
Step 4, check the four-figure version: drop the tenth digits to get 41 and 62, so the square is 4162. The six-figure reference must always sit inside that square, which is a quick check.
The mistake to watch for
A frequent slip is to write the northing first, because the eye tends to start at the upper edge.
Mistaken answer: 627413
The student read the numbers up the side first. This points to a different place: easting 62 and northing 41.
The correction is to say “along, then up” before you write anything. If your six-figure answer does not fall inside the four-figure square you worked out first, check the order again.
Check yourself
Use the same invented map style, then open each answer.
1. A school is 8 tenths of the way across from easting line 27 and 1 tenth up from northing line 54. Give the six-figure reference.
Show answer
Easting: 27 and 8 tenths gives 278. Northing: 54 and 1 tenth gives 541.
278541
2. Give the four-figure reference for the square containing the school in question 1.
Show answer
Drop the tenth digits: easting 27 and northing 54.
2754
3. A question asks for the grid reference of a whole grid square. Should you give four figures or six? Why?
Show answer
Four figures. A four-figure reference names a whole square, which is what the question asks for. Six figures would describe a spot inside the square, which is more precision than was requested.
Where this leads next
Next, learn how to use north and bearings consistently, so you can describe the direction from one grid reference to another. The mixed practice set then tests all five skills together, and the statistics and distribution explorer is handy when a question pairs a map with a table.
Some students can follow a grid reference in class but slip when the squares are small and the lines are crowded. A teacher on online one-to-one Geography tuition can see exactly how you read the lines and adjust from there.